The present invention relates to an optoelectronic scanning apparatus for a facsimile transceiver or the like.
An apparatus of this general type which is known in the art comprises a horizontal transparent glass platen over which an original document is scanningly fed by rollers or the like. A converging lens focusses a light image of a linear portion of the document perpendicular to the direction of movement onto a linear photosensor array located below the platen. A drive unit sequentially strobes the individual elements of the array to produce output signals corresponding to incident light intensity. A signal processing unit quantizes the signals to produce binary signals corresponding to light and dark areas of the document. The binary signals are fed to a remote facsimile transceiver to reproduce the document.
A major drawback of the prior art apparatus is that the photosensor array is disposed below the platen and faces upwardly. Thus, dust accumulates on the light receiving surface of the array due to the gravity. The dust partially obscures the photosensor elements and affects the quantization level in an uneven manner. Also, stray light and heat from a lamp used to illuminate the document reach the array and adversely affect the operation thereof. As yet another drawback, the vertical arrangement of the apparatus elements necessitates an undesirably large overall vertical size, and makes servicing of the elements awkward and difficult.